Regulation of steam temperature



March 3, 1936.

w. H, ARMACOST 2,032,391

REGULATION OF STEAM TEMPERATURE Filed May 26, 1953 T0 PRIME MovskINVENTOR Wilbur H. Armacost.

BY /7au;

ATTORNEY Patented Mar. 3, 1936 UNITED STATES PATENT OFFICE Wilbur H.Armacost, New York, N. Y., assignor to The superheater Company, NewYork, N. Y.

Application May 26, 1933, Serial No. 622,969

2 Claims.

My invention relates to regulation of steam temperature.

Experience in the operation of steam prime movers has shown thedesirability of utilizing steam at as high a temperature as possible.However, the construction of each prime mover sets a limit on thetemperature of steam which can be supplied to it and beyond which theprime mover is damaged as the temperature of the steam is increased.Various means have been proposed for regulating the temperature of thesteam some of which have met with considerable success, but none ofwhich are equally well adapted to all installations and it is an objectof my invention to provide a method and arrangement for supplying hightemperature steam which shall produce a close regulation of temperatureand which shall have a wide range of application.

In order that my invention may be fully and readily understood, I willnow describe in detail and in connection with the accompanying drawing aboiler plant for supplying superheated steam, such plant adapted tooperate in accordance with my novel method and selected by way ofexample from a number of possible embodiments of my invention. In thedrawing,

The figure is a sectional elevation, partly diagrammatic in character,of a boiler plant in accordance with my invention.

The plant illustrated in the drawing includes a plurality of generatingunits I0, I0 of known type, each having an integral superheater [2, I2and each connected to deliver superheated steam through one of thedischarge pipes l4, l4 to a superheated steam main I6 common to all theboilers of a given battery. Preferably, the superheaters 12 have arising temperature load characteristic, this being the ordinary thing,the steam temperature increasing with the load. The design andproportions of the boiler are such that the steam delivered from thesuperheaters 42 of the generating units l0, altho superheated, is not atas high a temperature as desired for final use in the prime mover.Moreover, its temperature ordinarily varies with the load. In accordancewith my invention, I raise the temperature of the steam delivered by thesuperheaters l 2 a varying amount depending on the load on boilers I0,and therefore on the temperature of the steam from superheaters l2, tomake the final steam temperature substantially that desired for use inthe prime mover and to maintain such temperature substantially constant.For these purposes, the steam from main [6 delivers through the normallyopen valve I8 to a conduit 20 which delivers in turn to a header 22.Header 22 serves as the inlet header for a superheater 24 having anoutlet header 26 which delivers into a conduit 28 from which steam flowsthrough normally open valve 33 into the main 32 for delivery to theprime mover. It will be seen that superheater 24 receives the steam froman entire battery of superheater boilers Ill. Superheater 24 is heatedby gases from furnace 34 which forms, preferably, part of a skeletongenerator 36 having a bank 10 of generating tubes 38, 38 betweensuperheater 24 and furnace 34. Bank 38 tempers the heat of the gasesfrom furnace 34 somewhat but not so much but what superheater 24 mayreadily add to the temperature of the steam received there- 15 by toraise it to the final temperature desired. When the temperature of steamdelivered from primary superheaters l2 tends to rise with the load, thetotal of the heat units needed to be supplied by the superheater 24 doesnot vary a great 20 deal with the load and the furnace 34 can beoperated nearly at a constant rate; My method of adding the finalsuperheat to the steam from a battery of superheat-er boilers by meansof a separate superheater is therefore particularly 25 well adapted tothe average boiler plant having integral superheaters since the greatmajority of present plants have a rising temperature load curve.

The steam generated in bank 38 is, however, 30 only at the temperaturecorresponding to its pressure and I take advantage of this fact toincrease the efficiency of the boiler 36 by passing the steam from suchboiler through a superheater 40 which lies in the path of gases fromfurnace 5 34 at a point immediately following superheater 24 in suchpath. The temperature of the furnace gases is thereby lowered while thetemperature of the steam from boiler 36 is raised approximately to thatcoming from superheaters l2 of boilers 40 I0. It is convenient to mixthe steam from superheated 40 with that from superheaters I2 in theinlet header 22 for superheater 24 and I have illustrated the units ofsuperheater 40 as connected directly to header 22. To further reduce the4:; temperature of the gases from furnace 34, I prefer to place someadditional heat absorbing means in the path of such gases at a pointfollowing the superheater 40. I have illustrated for this purpose ameans comp-rising an economizer 42, but 50 do not limit myself to this.

In the arrangement illustrated, a by-pass having a valve 44 therein, isplaced between the main l6 and the main 32. Such by-pass, however, willusually be closed. 55

The method of operation of the plant illustrated and disclosed hereinwill be clear from the foregoing description and will not berecapitulated.

It will be understood also that, while I have disclosed a specificarrangement, I do not limit myself in all cases to the details of suchdisclosure.

What I claim is:

1. The combination of a bank of boilers each provided with a superheaterin which the steam generated is superheated to a point approximating butsomewhat below the desired final superheated steam temperature; asuperheater generating unit having a gas path therethrough; steamgenerating means in said'path; a. superheater following said generatingmeans in saidpath; a second superheater in said gas path and connectedto receive the steam from said generating means, said second superheaterbeing positioned beyond said first superheater in said gas path so thatthe steamfrom said generating means issuperheated to a pointapproximating but somewhat below the final desired superheated steamtemperature; and connections for passing the steam from said secondsuperheater together with the steam partially superheated in thesuperheaters of said boilers to said first mentioned superheater forraising the temperature of steam passed therethrough to the desiredfinal superheated steam temperature.

2. The method of regulating the final temperature of superheated steamfrom a bank of boilers provided with superheaters having a risingtemperature characteristic which comprises generating steam in saidboilers, passing said steam through the superheaters associatedtherewith and heating it therein to a point approximating but somewhatbelow the final desired temperature, passing said partially superheatedsteam through the heat absorbing elements of a superheater firedseparately from said boiler superheaters for adding relatively smallamounts of heat to-said partially superheated steam, and controlling thefiring rate of said separately fired superheater to vary the additionalamount of superheat imparted to said partially superheated steam forattaining the desired final superheated steam temperature andmaintaining the latter substantially constant.

WILBUR' H. ARMACOST.

